UC Davis studies side effects of spaying and neutering

The Humane Society of the United States estimates nearly 80 percent of dogs with owners are now spayed or neutered. It's in part the result of tireless campaigning by animal shelters which are still forced to euthanize millions of animals a year.

"It's extremely important to spay and neuter our pets to prevent overpopulation," echoes pet owner Mark Johnsen, whose dog Teyla was in for a checkup.

But against that backdrop, an ongoing study at UC Davis is now raising questions about potential side effects from the procedures. Professor Benjamin Hart, DVM, PhD, and his team crunched records from the school of veterinary medicine's massive database, focusing specifically on golden retrievers.

"Because we know that breeds of dogs have different susceptibilities to cancers, they have different susceptibilities to joint problems," explains Hart.

Among the findings: More than double the rate of hip dysplasia in male golden retrievers neutered in their first year and more than triple the rate of a common canine cancer in both males and females that had first year surgeries.

"That were caused by or brought on by neutering," says Hart. "It increased in frequency."

While acknowledging the findings will be controversial, he believes they could argue for alternative methods of sterilization that are less likely to alter canine hormone levels, a potential cause of the bone growth and cancer issues.

"You could do vasectomy faster, less traumatic," he says. "You could do tubal ligation in females if you wanted to for less money and less trauma.".

Fellow UC Davis veterinarian Crystal Delano says she's interested in the findings. But she points out that spaying has been shown to lower the rates of other diseases such as mammary cancers, as well as producing other benefits.

"Neutering your animal can decrease some of the behavioral problems that occur when they're intact such as aggression," says Delano.

The study group also admits the findings are limited to the 759 golden retrievers in the study, and could vary dramatically breed by breed, leaving veterinarians and ultimately pet owners to weigh the pros and cons.

"I think it's something all pet owners would want to be aware of, says Mark Johnsen. "Because we love our pets, and want our pets to be with us forever, so I think we want to do the right thing."

The Davis team now plans to extend its research to Labradors, then move on to other popular breeds to identify any similarities or differences in the effects of spaying and neutering.

Written and produced by Tim Didion

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animal, UC, uc davis, health, carolyn johnson

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